The present invention relates to a household drip coffeemaker comprising a cold water reservoir supplying a water heater with continuous circulation, and a device adapted to treat the water contained in the reservoir with an anti-scaling agent that is soluble or in solution.
In a known coffeemaker of this type, the water treatment device comprises a cartridge which is arranged in the filling opening of the reservoir by being entirely maintained above the maximum filling level of the reservoir, which comprises a cover and a perforated bottom, and which contains a soluble anti-scaling agent of the type constituted conventionally by one or several polyphosphate crystals, whose dissolution can take place only during rapid flow of the water filling the reservoir. However, with this type of treatment device of the water with a polyphosphate crystal, it happens that the quantity of phosphorus which is added to the water is not absolutely controlled with precision to retard sufficiently over time the scaling of the water heater of the coffeemaker; thus, practice shows that in the case of habitual use of the coffeemaker (for example twice a day), the quantity of phosphorus added is substantially zero because the crystals have not the time to dissolve sufficiently between two cycles of operation of the coffeemaker, thus leading to rapid scaling of the water heater, whilst in the case of intensive use of the coffeemaker (for example all the time), the quantity of phosphorus added exceeds the value permitted by the laws in force, according to which the concentration of phosphorus in the water must be less than 5 mg/l expressed as P2 O5.
The invention has particularly for its object to overcome these drawbacks and to provide a household drip coffeemaker provided with a device for treating water with an anti-scaling agent that is soluble or in solution, whose added quantity in the water will be perfectly controlled while respecting the laws in force, and this no matter what the frequency of use of the coffeemaker and the solubility of the anti-scaling agent.
According to the invention, the water treatment device comprises a device for micro-dosing a quantity of anti-scaling agent which is predetermined as a function of the volume of water supplied to the water heater and which is injected into the water.
Thanks to this micro-dosing arrangement, the quantity of anti-scaling agent injected into the water is thereafter controlled with high reliability and, moreover, because of its injection at a very low dosage rate, has the unexpected result of retarding considerably over time the scaling of the water heater of the coffeemaker.